The present invention relates to an optical disk and optical disk processing apparatus, specifically a rewritable optical disk of which recording area is divided into a plurality of groups by annular boundaries, each of the above mentioned groups having a spare area having sectors which can be allocated in place of defective sectors of the disk, and an optical disk processing apparatus that is capable of recording and reproducing data from the optical disk.
The data zone format of the conventional optical disk will be described. FIG. 16 shows the data zone configuration of an optical disk described in “STANDARD ECMA-201, DATA INTERCHANGE ON 90 mm OPTICAL DISK CARTRIDGES.” Although the standard relates to the fully read-only type, partially rewritable type, and fully rewritable type, the following description relates only to the fully rewritable type.
Referring to the figure, a data zone contains four defect management areas (DMAs). Two of them are placed before a user area, and the other two are placed after the user area. Buffer tracks are disposed on the radially inward side of the defect management area 1 and on the radially outward side of the defect management area 4. An area between the defect management area 2 and defect management area 3 is referred to as a user area, which forms a recording/reproducing area where user data is recorded or reproduced. Each defect management area contains a disk definition structure (DDS), a primary defect list (PDL), and a secondary defect list (SDL). DDS is recorded in the first sector of each DMA after the disk is initialized. The information stored there includes a code indicating the disk type of each group such as rewritable or read-only, and the first addresses of PDL and SDL. PDL contains the addresses of all defective sectors detected at initialization. SDL is placed immediately after PDL and contains the addresses of defective sectors and the addresses of replacement sectors for use in management of defective sectors detected at recording. PDL and SDL are defect (management) information for managing defective sectors in the optical disk. The sizes of PDL and SDL are determined by the length of the information stored therein. Identical PDLs and identical SDLs are recorded in the four defect management areas of the disk.
DMAs are placed at positions having the first address values predetermined on the disk. FIG. 17 shows the positions of DMAs on the conventional optical disk. The ECMA-201, which is explained as an example, specifies fixed values, as shown in FIG. 17.
The ISO/IEC 15041 standard regarding the same type of optical disk with different capacity defines a similar group configuration with two options of 512 bytes per sector and 2048 bytes per sector. FIG. 18A and FIG. 18B show the positions of DMAs on another type of conventional optical disk. As shown in FIG. 18A and FIG. 18B, the disk has fixed values which are different from the values of the example described earlier.
The drive apparatus that is capable of reproduction from the two types of disks described above incorporates information indicating the storage positions of DMAs of the disk types in its firmware.
The size of the spare area in each zone of these disks is substantially proportional to the size of the user area in the same zone. FIG. 19 shows the size of spare area of the conventional ECMA-201 optical disk. As shown in the figure, the number of spare tracks is determined so that the ratio of the number of spare tracks to the number of data tracks will not be smaller than 0.2%. The spare areas are located at the ends of the respective zones.
In the apparatus that drives the optical disk medium as described above, the position information sent from the host as a parameter of a read/write instruction is a logical address, and this must be converted into a physical address by the drive. In addition, the group configuration must be specified to identify the location of replacement sectors for defective sectors.
Because the conventional optical disks are configured as described above, it is necessary to add or modify the firmware of the optical disk apparatus that controls the conversion between physical addresses and logical addresses and the defect management which controls the allocation of spare areas when a medium having a different group configuration is introduced.
Also, the size of the defect management area for each group is fixed, and the sizes of defect management areas of a disk of a particular group configuration may be greater than necessary for some applications.
When a medium having a new group configuration is introduced, an optical disk apparatus which can be used only with the conventional group configuration is not capable of reproduction from the medium of the new group configuration because the information indicating the position of the area containing the position information of defective sectors and of the area storing the information indicating the group configuration cannot be obtained from the disk.
Since data is usually recorded from a zone including a sector having a lowest logical address, zones including sectors with lower logical addresses have higher probabilities of using the spare area. However, the sizes of spare areas in the different zones of the disk are substantially proportional to the sizes of the user areas in the zones. Accordingly, the error rates of data recorded in the zones of the disk are not uniform.
The zone including the sector having the lowest logical address value, e.g, value “0”, contains various control data and requires a higher reliability. But because the size of the spare area in each zone of the disk is substantially proportional to the size of the user area in the zone, the reliability of the control data is insufficient.